1. Technical Field
This invention relates to security mail boxes that have signal devices to indicate when the mail has been delivered by monitoring the mail box door position.
2. Description of Prior Art
Prior art devices of this type have relied on a variety of ways to activate a signal once the mail box door is open and mail deposited within, see for example U.S. Pat. Nos. 5,388,759, 4,382,540, 4,262,830, 4,204,632, 4,089,460, 3,891,139, 3,556,394, 2,475,095 and 2,477,379.
In U.S. Pat. Nos. 4,089,640, 3,891,139, 3,556,394 and 2,477,379 all use magnets in release mechanisms in combination with activation elements.
In U.S. Pat. No. 4,089,640, for example, a shiftable weight and platform indicates the delivery of the mail.
U.S. Pat. No. 3,891,139 a spring urged rod that is released upon opening of the door moving an associated magnetic release, a signal panel on the opposite end of the box is thus displayed.
In U.S. Pat. No. 3,556,394 is directed to an electrical warning system in which a spring urged switch is released upon the door opening and closing, an electrical circuit activates an alarm.
U.S. Pat. No. 5,388,759 discloses a signal that is activated by gravity as the door opens, moving an attachment rod and gear assembly opening shutters to display a mail signal.
The remaining U.S. Patents cited hereinbefore rely on a variety of mechanical arrangements to indicate when the mail has been received including weights, see U.S. Patent ending in 098 spring plunger switches Patent ending in 632 and associated flags, see Patent ending in 839.